A gear-based mechanical metamaterial with continuously adjustable elastic parameters in a large range is provided. The gear-based mechanical metamaterial includes a gear array, a frame and connecting shafts. The gear array is formed by periodically extending mechanical metamaterial cells along an x direction and a y direction. Each of the mechanical metamaterial cells is formed by arranging a multiple gears. Adjacent gears of the multiple gears are meshed with each other. Each of the multiple gears includes a center hole and two centrosymmetric irregularly-shaped holes. A thickness of an elastic arm between the each of two centrosymmetric irregularly-shaped holes and an outer wall of a corresponding one of the multiple gears is uniformly increased or decreased. Each of the connecting shafts is arranged in a center hole of a corresponding one of the multiple gears.

A planetary gear mechanism is desired in which pinion gears can be inserted between support portions on both sides in the axial direction of the pinion gears after the support portions on both sides in the axial direction of the pinion gears are coupled together. In this planetary gear mechanism, a coupling inner portion of a carrier coupling portion is located between a first sun gear and a second sun gear in the axial direction, and a carrier and the carrier coupling portion are formed so that each pinion gears can be inserted between a first shaft support portion and a second shaft support portion in the axial direction from the outside in the radial direction.

A drivetrain for coupling a motor to a mixer shaft within a mixer includes a sun gear connectable to a rotor of the motor. The drivetrain also includes a plurality of stepped planetary gears. Each of the stepped planetary gears includes a first tooth section and a second tooth section. A first ring gear is mounted such that the first ring gear is fixed. The first ring gear and the sun gear are meshed with the stepped planetary gears at the first tooth section. A second ring gear is meshed with the stepped planetary gears at the second tooth section. The sun gear, the stepped planetary gears, the first ring gear, and the second ring gear collectively form a single stage planetary gear set of the drivetrain.

A drivetrain for coupling a motor to a mixer shaft within a mixer includes a sun gear connectable to a rotor of the motor. The drivetrain also includes a plurality of stepped planetary gears. Each of the stepped planetary gears includes a first tooth section and a second tooth section. A first ring gear is mounted such that the first ring gear is fixed. The first ring gear and the sun gear are meshed with the stepped planetary gears at the first tooth section. A second ring gear is meshed with the stepped planetary gears at the second tooth section. The sun gear, the stepped planetary gears, the first ring gear, and the second ring gear collectively form a single stage planetary gear set of the drivetrain.

A straddle vehicle comprises a shift drum formed with an engaged part; a transmission case formed with an insertion hole, a gear position sensor including an engagement part engageable with the engaged part; and a seal ring fitted to the outer peripheral surface of the gear position sensor, and the insertion hole includes a first inner peripheral surface with which the seal ring is in tight contact in a state in which the engagement part is engaged with the engaged part, and a second inner peripheral surface located closer to an entrance of the insertion hole than the first inner peripheral surface and having a diameter larger than a diameter of the first inner peripheral surface, and in a state in which the seal ring has reached an entrance of the first inner peripheral surface, at least a portion of the engagement part is fitted to the engaged part.

An improved planetary gear carrier assembly is disclosed including a carrier and a ring. The carrier has a hub extending in an axial direction. The hub has splines on a radially-outward facing surface that extend in an axial direction and further has a first set of groove sections on the radially-outward facing surface in which the first set of groove sections extends circumferentially around the hub and through the splines. The ring is received around the hub of the carrier and has splines on a radially-inward facing surface. The splines in the ring are received in the first set of groove sections by axially nesting the splines of the carrier and ring into one another and then angularly rotating the ring relative to the carrier. With the splines of the ring twisted in the groove sections of the carrier, the ring can be axially restricted relative to the carrier.

A method for attaching a gear driving part of this disclosure includes a first step of inserting a positioning bolt (23) into a positioning hole (21) of a first gear from a front side, and then screwing the positioning bolt into a screw hole (24) of a fixation-side member to regulate a phase of the first gear with respect to the fixation-side member; and a second step of inserting a portion of the bolt protruding to a front side of the first gear into a hole (22) of the gear case, and meshing the first gear with the second gear while positioning the fixation-side member in a predetermined phase position of the gear case.

A nesting structure supports a differential case. The nesting structure includes a first support structure that supports the differential case. The nesting structure includes a second support structure spaced apart from the first support structure to define a support opening. The support opening receives a first shim and establishes a first orientation between the first shim and the differential case in which the first shim is non-parallel with respect to a first bearing surface of the differential case.

Provided is a casing of a power transmission device which is capable of preventing a position of a gasket from being displaced without performing a complicated assembling process while suppressing an increase in a size of the entire power transmission device. A gasket (63) interposed between a TC side case member (61) and a TM side case member (62) has a first held portion (63a) which extends toward an inside of the TM side case member. A discharge mechanism (64) fixed to the TM side case member (62) has a first holding portion (64a1) which comes into contact with the first held portion (63a) from the TC side case member (61) side. The gasket (63) is held by the TM side case member (62) by sandwiching the first held portion (63a) between the TM side case member (62) and the first holding portion (64a1).

A gear drive device includes a first gear, and a second gear that meshes with the first gear to allow torque transmission. At least one of the first gear and the second gear includes a fan-type gear. The first gear and the second gear each include a guide portion, and the guide portion is configured to position the first gear and the second gear in a gear rotation direction upon installation thereof.